Needle Dislodgement Detection Systems and Methods

This application is a continuation of U.S. patent application Ser. No. 18/925,370, filed on Oct. 24, 2024, which claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 63/593,653, filed on Oct. 27, 2023, both of which are incorporated herein by reference in their entireties as if fully set forth herein.

The present disclosure generally relates to monitoring extracorporeal blood circuits. Particularly, but not exclusively, the present disclosure relates to methods and systems for monitoring extracorporeal blood circuits and identifying needle dislodgements.

Various devices are known in the field of medicine with which it is possible to remove fluids from the patient or supply fluids to the patient via a tube. Access to the patient is generally gained with a catheter inserted into bodily organs or with a cannula for puncturing blood vessels. Proper access to the patient must be ensured during the extracorporeal treatment. Therefore, it is necessary to monitor the patient's access.

Extracorporeal blood treatment devices, in particular those that involve an extracorporeal blood flow require proper access to the patient. Some extracorporeal blood treatment devices include, for example, dialysis systems and cell separators that require access to the vascular system of the patient. During extracorporeal blood treatment, blood is removed from the patient for instance using an arterial tube with an arterial puncture cannula, and the blood is re-supplied to the patient via a venous tube with a venous puncture cannula.

Needle dislodgement during an extracorporeal blood treatment (e.g., dialysis) is a rare event. However, if needle dislodgement is not detected quickly, particularly venous needle dislodgement (VND) it can lead to fatal blood loss in only a few minutes. For example, patients with a normal blood volume of 3-5 L subjected to the normal extracorporeal blood flow rate of 200-500 ml/min during dialysis, will likely suffer from fatal blood loss within 2-5 minutes after a VND. The reported number of VNDs per treatment falls within a wide range, from 0.0008% to 0.1% with an estimate that 10-33% of the VNDs lead to death.

A number of different access monitoring devices that function based on different principles have been developed and implemented. But these conventional approaches suffer from a number of shortcomings. In some such conventional approaches, the venous line pressure is measured in various ways to try to detect a VND based on an abrupt decrease in the venous line pressure. However, such pressure-monitoring approaches are not robust because sometimes a VND or partial VND leads to only a small pressure change in the venous return line. Conventional pressure monitoring systems with sufficient sensitivity to detect such small pressure changes have been utilized, but such systems require sufficient damping or averaging to reduce noise in the measurement, which would otherwise adversely affect the systems' response time. Moreover, these systems typically suffer from many false positives, thus increasing the burden of monitoring and addressing false alarms. Another approach is to place wetness detectors at or near a patient's access point, which would send an alert after blood has leaked and collected at the detector. Wetness detectors are also less than optimal because a misplaced detector can defeat such a system and the path of a leak cannot always be reliably predicted. Mechanical tube constriction devices are also less than optimal because of the potential for improper implementation.

A need exists for a reliable, robust, and cost-effective solution for detecting needle dislodgements, in particular, venous needle dislodgements for extracorporeal blood treatments.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to necessarily identify key features or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter.

The present disclosure describes needle dislodgement detection systems and methods that address conventional shortcomings. For example, the systems according to the present disclosure can provide a more reliable, robust, rapid, and cost-effective solution for detecting needle dislodgements.

In one example, a method of monitoring an extracorporeal blood circuit of a patient and identifying a needle dislodgement comprises identifying a potential needle dislodgement event based on changes in pressure of the extracorporeal blood circuit; searching for a heart rate of a patient by analyzing an optical backscatter signal from an optical sensor attached to the extracorporeal blood circuit; and verifying the potential needle dislodgement event is a needle dislodgement based on the absence of the heart rate.

Alternatively or additionally to any of the examples above, the method can further include reducing a speed of a blood pump for the extracorporeal blood circuit when the potential needle dislodgement event is identified; and searching for the heart rate of the patient while the blood pump is at the reduced speed. Alternatively or additionally to any of the examples above, the speed of the blood pump can be reduced to a blood flow rate of between about 50-120 mL/min or about 100-170 mL/min when the potential needle dislodgement event is identified. Alternatively or additionally to any of the examples above, the method can further include verifying the potential needle dislodgement event is not a needle dislodgement based on the presence of the heart rate of the patient. Alternatively or additionally to any of the examples above, the method can include returning the blood pump to a previous speed following verification that the potential needle dislodgement event is not a needle dislodgement. Alternatively or additionally to any of the examples above, the potential needle dislodgement event can be identified by an algorithm that calculates a needle dislodgement value based on a maximum arterial pressure difference, a venous pressure change, the arterial pressure, and the venous pressure, and when the needle dislodgement value is below a threshold value the algorithm identifies the potential needle dislodgement event. Alternatively or additionally to any of the examples above, the optical backscatter signal can be representative of the detected backscatter of RED wavelength light energy. Alternatively or additionally to any of the examples above, the heart rate of the patient can be searched for using an algorithm that analyzes the optical backscatter signal by: filtering data from the optical backscatter signal to produce filtered optical backscatter data (FOBD); computing a peak to peak (PTP) value by subtracting min FOBD from max FOBD; computing a prominence value based on PTP value; identifying and indexing peaks from the FOBD with a prominence above a prominence threshold (PT) and a distance between each peak above a minimum peak distance (min PD); calculating peak times when more than one peak is indexed; and calculating the heart rate based on the peak times. Alternatively or additionally to any of the examples above, the method can further include verifying the potential needle dislodgement event is not a needle dislodgement based on the presence of the heart rate (HR) within a set HR range, a variance of the FOBD within a set variance range, and a blood pump rate (BPR) within a set BPR range. Alternatively or additionally to any of the examples above, the method can further include identifying an arterial heart rate of the patient by analyzing changes in the arterial pressure of the extracorporeal blood circuit, wherein the set HR range is determined based on the identified arterial heart rate. Alternatively or additionally to any of the examples above, verifying the potential needle dislodgement event can be further based on the presence of the arterial heart rate within a set arterial HR range. Alternatively or additionally to any of the examples above, the optical sensor can be attached to a venous line of the extracorporeal blood circuit and the needle dislodgement is a venous needle dislodgement.

In another example, a system for detecting a needle dislodgement of an extracorporeal blood circuit of a patient comprises a computing device; a processor; a memory comprising instructions, when executed by the processor cause the system to: receive a venous pressure signal, an arterial pressure signal, and an optical backscatter signal from an optical sensor attached to a venous line of the extracorporeal blood circuit; identify a potential needle dislodgement event based on changes in the arterial pressure signal and the venous pressure signal; search for a heart rate of the patient by analyzing the optical backscatter signal; and verify the potential needle dislodgement event is a needle dislodgement based on the absence of the heart rate.

Alternatively or additionally to any of the examples above, the memory comprising instructions, when executed by the processor can cause the system to: reduce a speed of a blood pump for the extracorporeal blood circuit when the potential needle dislodgement event is identified; and search for the heart rate of the patient while the blood pump is at the reduced speed. Alternatively or additionally to any of the examples above, the speed of the blood pump can be reduced to a blood flow rate between about 50-120 mL/min or about 100-170 mL/min when the potential needle dislodgement event is identified. Alternatively or additionally to any of the examples above, the memory comprising instructions, when executed by the processor can cause the system to verify the potential needle dislodgement event is not a needle dislodgement based on the presence of the heart rate. Alternatively or additionally to any of the examples above, the memory comprising instructions, when executed by the processor can cause the system to return the blood pump to a previous speed following verification that the potential needle dislodgement event is not a needle dislodgement. Alternatively or additionally to any of the examples above, the memory comprising instructions, when executed by the processor can cause an algorithm to calculate a needle dislodgement value based on a maximum arterial pressure difference, a venous pressure change, an arterial pressure, and a venous pressure, and when the needle dislodgement value is below a threshold value the algorithm identifies the potential needle dislodgement event. Alternatively or additionally to any of the examples above, the optical backscatter signal can be representative of the detected backscatter of RED wavelength light energy. Alternatively or additionally to any of the examples above, the memory comprising instructions, when executed by the processor can cause an algorithm to search for the heart rate of the patient by analyzing the optical backscatter signal, the steps of the algorithm comprise: filtering data from optical backscatter signal to produce filtered optical backscatter data (FOBD); computing a peak to peak (PTP) value by subtracting min FOBD from max FOBD; computing a prominence value based on PTP value; identifying and indexing peaks from the FOBD with a prominence above a prominence threshold (PT) and a distance between each peak above a minimum peak distance (min PD); calculating peak times when more than one peak is indexed; and calculating the heart rate based on the peak times. Alternatively or additionally to any of the examples above, the memory comprising instructions, when executed by the processor, can cause the system to verify the potential needle dislodgement event is not a needle dislodgement based on the presence of the heart rate (HR) within a set HR range, a variance of the FOBD within a set variance range, and a blood pump rate (BPR) within a set BPR range. Alternatively or additionally to any of the examples above, the optical sensor can be attached to a venous line of the extracorporeal blood circuit and the needle dislodgement is a venous needle dislodgement.

In another example, a computer-readable memory storage device of a needle dislodgement detection system for monitoring an extracorporeal blood circuit of a patient, comprises instructions, which when executed by a processor, cause the needle dislodgement detection system to: receive venous pressure data, arterial pressure data, and optical backscatter data from an optical sensor attached to a venous line of the extracorporeal blood circuit; identify a potential needle dislodgement event based on changes in the arterial pressure and the venous pressure; search for a heart rate of a patient by analyzing the optical backscatter signal; and verify the potential needle dislodgement event is a needle dislodgement based on the absence of the heart rate.

In another example, a dialysis machine comprises a blood pump; an extracorporeal blood circuit configured to connect the blood pump and a dialyzer to a patient; an arterial pressure monitor and a venous pressure monitor; an optical sensor attached to a venous line of the extracorporeal blood circuit; a computing device comprising a processor and a memory, the computing device being configured to: receive a venous pressure signal from the venous pressure monitor, an arterial pressure signal from the arterial pressure monitor, and an optical backscatter signal from the optical sensor; identify a potential needle dislodgement event based on changes in the arterial pressure and venous pressure; search for a heart rate of a patient by analyzing the optical backscatter signal; and verify the potential needle dislodgement event is a needle dislodgement based on the absence of the heart rate.

Alternatively or additionally to any of the examples above, the computing device can be configured to: reduce a speed of a blood pump for the extracorporeal blood circuit when the potential needle dislodgement event is identified; and search for the heart rate of the patient while the blood pump is at the reduced speed. Alternatively or additionally to any of the examples above, the speed of the blood pump can be reduced to between about 50-120 mL/min or about 100-170 mL/min when the potential needle dislodgement event is identified. Alternatively or additionally to any of the examples above, the computing device can be configured to verify the potential needle dislodgement event is not a needle dislodgement based on the presence of the heart rate. Alternatively or additionally to any of the examples above, the computing device can be configured to return the blood pump to a previous speed following verification that the potential needle dislodgement event is not a needle dislodgement. Alternatively or additionally to any of the examples above, the computing device can be configured to execute a needle dislodgement algorithm that calculates a needle dislodgement value based on a maximum arterial pressure difference, a venous pressure change, an arterial pressure, and a venous pressure, and when the needle dislodgement value is below a threshold value the computing device identifies the potential needle dislodgement event. Alternatively or additionally to any of the examples above, the optical backscatter signal can be representative of the detected backscatter of RED wavelength light energy. Alternatively or additionally to any of the examples above, the heart rate of the patient can be searched for using an algorithm that analyzes the optical backscatter signal by: filtering data from optical backscatter signal to produce filtered optical backscatter data (FOBD); computing a peak to peak (PTP) value by subtracting min FOBD from max FOBD; computing a prominence value based on PTP value; identifying and indexing peaks from the FOBD with a prominence above a prominence threshold (PT) and a distance between each peak above a minimum peak distance (min PD); calculating peak times when more than one peak is indexed; and calculating the heart rate based on the peak times. Alternatively or additionally to any of the examples above, the needle dislodgement is a venous needle dislodgement.

In another example, a method of identifying a potential needle dislodgement of an extracorporeal blood circuit based on arterial pressure data and venous pressure data, comprises: filtering the arterial pressure data and the venous pressure data to reduce noise; calculating current filtered arterial pressure data values (FAPD) based on at least three arterial pressure data values; calculating current filtered venous pressure data (FVPD) value based on at least three venous pressure data values; storing a queue of the current FAPD values and a discrete set of the current FVPD values; calculating a maximum arterial pressure (MAD) difference from the queue of stored current FAPD values; calculating a venous pressure change (VPC) that is the difference between the current FVPD minus the average FVPD of the queue of current FVPD; calculating a venous dislodgement value based on the VPC, the MAD, the current FAPD, and the current FVPD; and identifying a potential needle dislodgement when the venous dislodgement value is below a set threshold.

Alternatively or additionally to any of the examples above, the method further includes identifying an arterial heart rate of the patient by analyzing changes in the arterial pressure of the extracorporeal blood circuit, wherein filtering of the venous pressure data includes utilizing a lock-in signal processing technique based on the arterial heart rate.

In another example, a method of identifying and calculating a heart rate of a patient by analyzing an optical backscatter signal from an optical sensor attached to an extracorporeal blood circuit for the patient, comprises: filtering data from optical backscatter signal to produce filtered optical backscatter data (FOBD); computing a peak to peak (PTP) value by subtracting min FOBD from max FOBD; computing a prominence value based on PTP value; identifying and indexing peaks from the FOBD with a prominence above a prominence threshold (PT) and a distance between each peak above a minimum peak distance (min PD); calculating peak times when more than one peak is indexed; and calculating the heart rate based on the peak times.

Alternatively or additionally to any of the examples above, the method further includes reducing a speed of a blood pump for the extracorporeal blood circuit to a blood flow rate between about 50 mL/min and 120 mL/min or between about 100 to 170 mL/min prior to identifying and calculating the heart rate of the patient.

In another example, a method of identifying and calculating a heart rate of a patient connected to an extracorporeal blood circuit by analyzing a pressure signal from a pressure monitor attached to the extracorporeal blood circuit, comprises: filtering data from the pressure signal to produce filtered pressure data (FPD); computing a peak to peak (PTP) value by subtracting min FPD from max FPD; computing a prominence value based on PTP value; identifying and indexing peaks from the FPD with a prominence above a prominence threshold (PT) and a distance between each peak above a minimum peak distance (min PD); calculating peak times when more than one peak is indexed; and calculating the heart rate based on the peak times.

In another example, a method of monitoring an extracorporeal blood circuit of a patient and identifying a needle dislodgement, comprises: identifying a potential needle dislodgement event based on changes in pressure of the extracorporeal blood circuit; searching for a heart rate of a patient by analyzing changes in the pressure of the extracorporeal blood circuit; and verifying the potential needle dislodgement event is a needle dislodgement based on the absence of the heart rate; wherein the heart rate of the patient is searched for by analyzing a pressure signal from a pressure monitor attached to the extracorporeal blood circuit, the steps of which include: filtering data from the pressure signal to produce filtered pressure data (FPD); computing a peak to peak (PTP) value by subtracting min FPD from max FPD; computing a prominence value based on PTP value; identifying and indexing peaks from the FPD with a prominence above a prominence threshold (PT) and a distance between each peak above a minimum peak distance (min PD); calculating peak times when more than one peak is indexed; and calculating the heart rate based on the peak times.

In another example, a method of monitoring an extracorporeal blood circuit of a patient and identifying a needle dislodgement, comprises: identifying a potential needle dislodgement event based on changes in an arterial pressure and/or a venous pressure of the extracorporeal blood circuit; identifying an arterial heart rate of the patient by analyzing changes in an arterial pressure of the extracorporeal blood circuit; searching for a venous heart rate of a patient by analyzing changes in the venous pressure of the extracorporeal blood circuit, wherein the searching is enhanced based on the identified arterial heart rate; and verifying the potential needle dislodgement event is a needle dislodgement based on the absence of the venous heart rate.

Alternatively or additionally to any of the examples above, analyzing changes in venous pressure can include utilizing a lock-in signal processing technique to filter the venous pressure data. Alternatively or additionally to any of the examples above, the venous heart rate of the patient is searched for using an algorithm that analyzes the venous pressure by: filtering data from a venous pressure signal to produce filtered pressure data (FPD); computing a peak to peak (PTP) value by subtracting a min FPD from a max FPD; computing a prominence value based on the PTP value; identifying and indexing peaks from the FPD with a prominence above a prominence threshold (PT) and a distance between each peak above a minimum peak distance (min PD); calculating peak times when more than one peak is indexed; and calculating the venous heart rate based on the peak times. Alternatively or additionally to any of the examples above, the method can further include verifying the potential needle dislodgement event is not a needle dislodgement based on the presence of the venous heart rate (HR) within a set venous HR range, a variance of the FPD within a set variance range, and a blood pump rate (BPR) within a set BPR range. Alternatively or additionally to any of the examples above, the set venous HR range can be determined based on the identified arterial heart rate. Alternatively or additionally to any of the examples above, verifying the potential needle dislodgement event is not a needle dislodgement can further be based on the presence of the arterial heart rate within a set arterial heart rate range.

The foregoing has broadly outlined the features and technical advantages of the present disclosure such that the following detailed description of the disclosure may be better understood. It is to be appreciated by those skilled in the art that the embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. The novel features of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

The devices and methods explained in the present disclosure involve the use of sensors (e.g., pressure and optical) to monitor extracorporeal blood circuits, detect and measure a heart rate of a patient, and detect a needle dislodgement.

illustrates a schematic of an extracorporeal blood circuit, in accordance with non-limiting examples of the present disclosure. As shown in, blood may be drawn from an arm of a patient through an arterial lineconnected to the patient via an arterial access(e.g., needle, catheter, cannula). Blood may be returned to the patient after it is treated via a venous lineand a venous access(e.g., needle, catheter, cannula). Extracorporeal blood circuitmay further include, among other things, an arterial pressure monitor, a blood pump, a blood treatment device, a venous pressure monitor, and an optical sensor. Tubing may be used for one or more sections (arterial line, venous line) of the extracorporeal blood circuit.

As shown in, arterial pressure monitormay be connected to the arterial linebetween arterial accessand blood pump, and configured to measure pressure of blood within arterial line(i.e., arterial pressure) and transmit an arterial pressure signal. Blood pumpmay be configured to pump blood through extracorporeal blood circuit, including blood treatment device. The flow rate of blood through circuitmay be adjustable by increasing or decreasing the speed of blood pump. For example, the speed of blood pump may be controllable to produce a blood flow rate from 0 mL/min up to about 600 mL/min, or greater. Blood pumpmay be, for example, a rotary pump or roller pump, or other suitable type pump. Blood treatment devicemay take a variety of forms, including for example, a dialyzer that may be used for dialysis (e.g., hemodialysis). Venous pressure monitormay be positioned along the venous linebetween blood treatment deviceand venous access, and configured to measure pressure of blood within venous line(i.e., venous pressure) and transmit a venous pressure signal

Optical sensormay be configured to releasably receive and/or couple to venous line, for example, between venous pressure monitorand venous access. Optical sensormay couple to the outside of venous line, which enables a non-invasive, air-free connection to venous line. Optical sensormay be configured to transmit light energy at one or more wavelengths into venous lineand the blood flow. For example, optical sensormay transmit light energy at RED wavelength, IR wavelength, green, blue wavelength, or other wavelengths. For example, optical sensormay include one or more light sources (e.g., LEDs) and a first light source may output RED wavelength while a second light source may output IR wavelength. Optical sensormay also detect backscattering of the transmitted light energy (e.g., RED, green, blue and/or IR), and generate an optical backscatter signal. Optical backscatter signalmay include a single signal and/or multiple signals. For example, optical backscatter signalmay include a RED backscatter signal, an IR backscatter signal, green backscatter signal, blue backscatter signal, separate RED, IR, blue, and/or green backscatter signals, or a combined backscatter signal. A variety of optical sensors may be suitable, one example, includes MAX30102, which is available from Maxim Integrated Products, Inc.

Optical scattering from blood (pulsatile flow) in a tube can be detected using the optical sensor. The optical backscattering from the blood detected by the optical sensor can be a result of light scattering from a small region of blood near the tube inner surface, which can be based on the optical penetration depth. The flow profile of blood in the tube, the associated red blood cell concentration, and the red blood cell shape can change during each pulse of pulsatile blood flow in the tube of the extracorporeal blood circuit, and this can be detected by the optical back scattering by the optical sensor.

As shown in, a needle dislodgement detection system, may be configured to receive optical backscatter signalfrom optical sensor, arterial pressure signal, and venous pressure signal

illustrates a block diagram of needle dislodgement detection (NDD) system, in accordance with non-limiting examples of the present disclosure. NDD systemmay include, among other things, a computing deviceand a data repository.

The data repositorycan represent one or more systems storing data that may be accessed and provided to the computing deviceas further described herein. Although illustrated as separate from the computing device, some or all the components of the data repositorymay be components of the computing device.

Computing devicemay include, among other things, a processor, a memory, and I/O devices. Processormay include circuitry or processor logic, such as, for example, any of a variety of commercial processors. In some examples, processormay include multiple processors, a multi-threaded processor, a multi-core processor (whether the multiple cores coexist on the same or separate dies), and/or a multi-processor architecture of some other variety by which multiple physically separate processors are in some way linked. Additionally, in some examples, the processormay include graphics processing portions and may include dedicated memory, multiple-threaded processing and/or some other parallel processing capability. In some examples, the processormay be an application specific integrated circuit (ASIC) or a field programmable integrated circuit (FPGA).

Memorymay include logic, a portion of which includes arrays of integrated circuits, forming non-volatile memory to persistently store data or a combination of non-volatile memory and volatile memory. It is to be appreciated, that the memorymay be based on any of a variety of technologies. In particular, the arrays of integrated circuits included in memorymay be arranged to form one or more types of memory, such as, for example, dynamic random access memory (DRAM), NAND memory, NOR memory, or the like.

I/O devicescan be any of a variety of devices to receive input and/or provide output. For example, I/O devicescan include, a keyboard or keypad, a display (e.g., touch, non-touch, or the like), an LED, or the like.

Network interfacecan include logic and/or features to support a communication interface. For example, network interfacemay include one or more interfaces that operate according to various communication protocols or standards to communicate over direct or network communication links. Direct communications may occur via use of communication protocols or standards described in one or more industry standards (including progenies and variants). For example, network interfacemay facilitate communication over a bus, such as, for example, peripheral component interconnect express (PCIe), non-volatile memory express (NVMe), universal serial bus (USB), system management bus (SMBus), SAS (e.g., serial attached small computer system interface (SCSI)) interfaces, serial AT attachment (SATA) interfaces, or the like. Additionally, network interfacecan include logic and/or features to enable communication over a variety of wired or wireless network standards (e.g., 802.11 communication standards). For example, network interfacemay be arranged to support wired communication protocols or standards, such as, Ethernet, RS-232, or the like. As another example, network interfacemay be arranged to support wireless communication protocols or standards, such as, for example, Wi-Fi, Bluetooth, ZigBee, LTE, 5G, or the like.

Memorycan include instructions. During operation, processorcan execute instructionsto cause the computing deviceto access data from the repository, for example, current and/or historical data for optical backscatter signal, arterial pressure signal, and venous pressure signal, each of which may reside in records within one or more data repositoriesor kept within memory. Instructions can include the various methods and processes (e.g., process,,,,,,,,) discussed further herein.

The processofshows steps for monitoring an extracorporeal blood circuit of a patient (e.g., circuit) and identifying a needle dislodgement, according to some implementations of the present disclosure. Processmay be performed, for example, by NDD system, or other devices and systems (e.g, dialysis systemof) described herein. At step, processcan identify a potential needle dislodgement event based on pressure change (e.g., arterial and/or venous pressure) in the extracorporeal blood circuit. There are different techniques that may be used to identify a potential needle dislodgement event based on pressure change. Processdescribed further herein in reference to, is one example of how stepmay be performed.

Process, at stepcan check for a heart rate of a patient by analyzing an optical backscatter signal (e.g.,) from an optical sensor (e.g., optical sensor) attached to extracorporeal blood circuit. Processand Processare described further herein in reference to, and are examples of how stepmay be performed.

Process, at step, can verify the potential needle dislodgement event is an actual needle dislodgement based on the absence of the heart rate. For example, if no heart rate is identified (e.g., by step) then the potential needle dislodgement can be verified as an actual needle dislodgement. If a heart rate is identified, then the potential needle dislodgement can be verified as a false positive. In response to verification of a needle dislodgement, NDD systemmay initiate appropriate actions and alarms, alternatively, in response to verification of a false positive, NDD systemmay clear or reset the potential needle dislodgement alarm (e.g., triggered by step).

Processofshows steps for monitoring an extracorporeal blood circuit of a patient (e.g., circuit) and identifying a needle dislodgement, according to some implementations of the present disclosure. Processmay be performed, for example, by NDD system, or other devices and systems described herein. Processmay include some of the same steps as process, while also including some different and/or additional steps. At stepof process, the pressure (e.g., the arterial pressure and/or venous pressure) of the extracorporeal blood circuit may be monitored. For example, arterial pressure signaland venous pressure signalmay be received and analyzed to search for a potential needle dislodgement event. At step, processcan check if a potential needle dislodgement has been identified. At step, if a potential needle dislodgement has not been identified (i.e., step, “No”), then processcan return to stepand processcan continue. At step, if a potential needle dislodgement has been identified (i.e., step, “Yes”), processmay proceed to step. Processdescribed further herein in reference to, is one example of a process that may be used to perform stepand/or step.

At step, the speed of the blood pump may be reduced. For example, the speed of blood pump may be reduced such that the blood flow rate is less than about 200 mL/min, about 150 mL/min, about 125 mL/min, about 100 mL/min, about 75 mL/min, or about 50 mL/min, or a speed between about 130-170 mL/min, about 150-200 mL/min, about 125-150 mL/min, about 100-125 mL/min, about 75-100 mL/min, about 50-75 mL/min, or about 50-120 mL/min. In some implementations, the speed of the blood pump may be reduced such that the flow rate drops to about 0 mL/min. The speed of the blood pump may be reduced rapidly, for example, in less than about 10 seconds, 5 seconds, 4 seconds, 3 seconds, 2 seconds, or 1 second. At step, the optical backscatter signal can be analyzed and used to search for and verify if a heart rate of the patient is detected. Processand processare described further herein in reference to, and together are an example of how stepmay be performed. At step, if a heart rate of the patient is detected (i.e., Step, “Yes”), then it can be confirmed that the identified potential needle dislodgement is a false alarm, and processmay proceed to step. At step, the blood pump speed can be increased in order to return the blood pump to its previous operating speed (e.g., speed prior to step), and then processcan return to step. At step, if a heart rate of the patient is not detected (i.e., Step, “No”), then it can be confirmed that the identified potential needle dislodgement is an actual needle dislodgement and processcan proceed to step. At step, processcan stop the blood pump and activate a needle dislodgement alarm state, and/or initiate other appropriate responsive action.

Processofshows the steps for identifying a potential needle dislodgement event based on pressure change in the extracorporeal blood circuit, according to some implementations of the present disclosure. For example, processmay be utilized to perform stepas shown in, steps/of, stepof, and/or steps/of. Processmay be performed, for example, by NDD system, or other devices and systems (see e.g., dialysis systemof) described herein.

Identifying a needle dislodgement event based on pressure change can be challenging due to the variability in the pressure due to a number of factors. Blood loss caused by a needle dislodgement of the venous line will cause venous pressure to drop; however, other things may also cause the venous pressure to drop, for example, vertical movement of the patient's arm. Additionally, treatment conditions and other system components of a dialysis system may also impact pressure, including for example, the blood pump, ultrafiltration pump, substitution pump, and balance chamber.

Process, at stepcan include processing, for example through a filter, raw arterial pressure data and venous pressure data received via arterial pressure signaland venous pressure signal. Processing may include filtering the raw data, for example, through a low pass filter to minimize the noise in the data. The processed pressure data values (e.g., PPD1, PPD2, PPD3, PPD . . . ) may be stored, for example, in data repositoryand/or memory. The raw arterial and venous pressure data may be sampled at a frequency, for example, of once per second, 2 times per second, 5 times per second, 10 times per second, 20 times per second, 30 times per second, or greater.

Stepmay include using the respective arterial and venous processed pressure data to compute and store a queue of current arterial filtered pressure data values and current venous filtered pressure data values. Current filtered pressure data (FPD) of each may be computed based on one or more previous PPD values (e.g., PPD1, PPD2, PPD3). For example, function 1 below may be used to calculate FPD:

Constant values kand kcan be adjusted based on the desired level of smoothing. Function 1 can be executed and repeated for both arterial PPD and venous PPD values establishing a queue of current arterial filtered pressure data (AFPD) and a queue of current venous filtered pressure data (VFPD). The queue of current AFPD or VFPD values can include greater than 100 values, 150 values, 200 values, 250 values, or 300 values. For example, according to one implementation, a queue may include 280 AFPD values or 280 VFPD values corresponding to a duration of 14 seconds of data sampled at a rate of 20 times per second. Other sample rates and/or number of samples may be used for other implementations. Each queue of data (i.e., AFPD and VFPD) may be constantly updated as new data is received and new FPD values are computed thereby replacing the oldest data.

Stepcan include calculating and storing a maximum arterial pressure difference (MAD), based on the maximum and minimum AFPD from the queue of AFPD. This may be calculated, for example, using function 2 below: